Examines the relationship between premarital cohabitation and marital dysfunction a sample spouses in two marriage cohorts: those married between 1964 and 1980 (when cohabitation was less common) and those married between 1981 and 1997 (when cohabitation was more common). Spouses in both cohorts who cohabited prior to marriage reported poorer marital quality and greater marital instability. (Contains 45 references and 2 tables.) (GCP)